My 60 year old home has fiberglass in the
exterior wall cavity, but it's not in great shape (I saw some of it during a
kitchen and bathroom redo). I added blown-in insulation in the attic 2 year
ago. Will blown-in insulation work in exterior wall cavities if fiberglass is
already there?

Mike
North Wales, PA

It would work with existing insulation but the
problem in installing it. It would be almost impossible to blow insulation
into the wall cavities with existing insulation already in place.

You have quite a project ahead of you. The
insulation you have in place would need to be removed.

You could remove the drywall but
that would be a costly ordeal. If you have siding you could try removing some of
the boards and try to pull the existing insulation out. If you're able to remove
it you could then follow my procedures for blowing insulation into covered walls
by clicking here.

Retrofit projects such as yours are
sometimes tough to do and can be costly. If you're unable to remove the
insulation you might want to consider applying a wall covering. You can find
these at your local home improvement store. I don't know much about these and
can't attest as to how well they work but they claim to have a R-Value from R-3
to R-5. That's not what you're trying to achieve but at least it would be better
than what you have at the moment.